Process for the removal of glaze from fabric



March 29, 1960 D. SWAN I 2,930,099

PROCESS FOR THE REMOVAL OF GLAZE FROM FABRIC Filed July 12, 1954 A A A/ A A y v v v v v v |23456T89|0x xx INVENTOR LEWIS DELMAR SWAN BY Maw ATTORNEY PRQCESS FQR THE REMOVAL OF FROM FABRIC Lewis Delmar Swan, Wilmington, Del assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Application July 12, 1954, Serial No. 442,702

2 Claims. (Cl. 261) GLAZE This invention relates to a process for the treatment of a fabric containing yarn produced from a thermoplastic, synthetic, linear polymer. More specifically it is concerned with a process for the removal of glaze from such fabrics.

It is an object of the present invention to provide a process for the removal of glaze from a fabric containing yarn produced from synthetic thermoplastic linear polymer.

Another object is to provide a process for increasing the bulk of such fabrics.

These and other objects will become apparent in the course of the following specification and claims.

By the term fabric containing a yarn produced from a thermoplastic, synthetic, linear polymer is meant any fabric containing either yarn which is spun entirely from or contains a substantial proportion of staple produced from a synthetic, thermoplastic, linear polymer or copolymer, or containing continuous filament yarn produced from a synthetic, thermoplastic, linear polymer or copolymer. Among such materials may be mentioned the polyamides such as polyhexamethylene adipamide, the polyesters, such as polyethylene terephthalate, addition polymers such as the polyacrylonitriles, copolymers of each of the above, and the like. By glaze is meant the mirror-like finish or shine which is produced upon fabrics by heat and pressure, particularly along seams and in general in regions of multiple fabric layers. This glaze or shine is due to the flattening of the crown of the yarn bundle presenting a continuous surface which concentrates reflected light. While the problem is experienced to some extent with all types of fabric, it is particularly acute in the case of fabrics containing yarn produced from a synthetic, thermoplastic, linear polymer.

The invention will be more readily understood by reference to the drawings. 7

Figure is a diagrammatic representation of'a magnified view of an elevational section of a glaze-free fabric.

Figure 2 is a diagrammaticrepresentation of a magnified view of an elevational section of a fabric having glaze.

Figure 3 is a graph upon which is compared the thickness of a fabric upon which glaze is impressed at various temperatures with its thickness after treatment in accordance with the process of-the present invention.

Figure 4 is a graph showing the effect upon fabric thickness of repeated glaze impression followed bytreatrnent in accordance with the process of the present invention.

The smooth, sinusoidal character of the yarn path in a woven, glaze-free fabric is demonstrated in Figure l. The yam bundles and the staple fibers from which they are spun are essentially round in cross-section. When such a fabric is subjected to heat and pressure as in-pressing during commercial drycleaning operations, the yarn bundles tend to become flattened along their exposed surfaces. The effect is illustrated in Figure 2 wherethe 5 yarn bundles are seen to have been flattened at their This flat, relatively smooth surface;

exposed surfaces. concentrates refiected'light and causes the commonly known as shine or glaze. a

In accordancewith the present invention a process is provided wherein the glaze impressed upon a fabric containing a yarn produced froma thermoplastic, synthetic, linear polymer is removed by subjecting the saidfabric phenomenon in a relaxed condition to a temperature at least about the temperature of glaze impression and below the temperature at which fusionoccurs. By temperature of glaze impression is meant that temperature at which the glaze is imparted to the fabric. It is preferred to employ a temperature no lower than the glaze impression temperature. Dry air is the preferred medium during the glaze removal operation. Glaze removal is accompanied by an increase in fabric bulk. a

The following examples are cited to illustrate the invent ion. They are not intended to limit it in any manner. Unless otherwise designated, the fabric employed is a 7 ounce per square yard, 2 x 2 navy blue twill, hav-- ing a Greige count of 64 x 56 and a Greige width of 52%", woven from a yarn having a cotton count, 30/2 and a 2/8 twist'of 19/17. The yarn is spun from a 2 /2", 3 denier per filament, semi-dull luster staple of a copolymer of 94% acrylonitrile and 6% methyl acrylate. A circular glazed spot 3 /2 inches in diameter is induced upon 6 x 7 inch test swatchesusing an arbor truss, hav

ing a controllable heating element-and adapted to pro-,

duce pressures up to 160 p.s.i. -A of .0.5 p.s.i. is employed in forming each spot. The numerals in Tablel indicate Glaze Level and range from 0 for glaze-free to 4 which represents a very objectionable glaze. The numeral 1 denotes a marginal glaze-free condition. In each example of Table I after the glazed spot vis im- 40 pressed, the swatch is hung for two minutes in a circulating air over regulated at 160 C. t t

TABLE I Before Glaze After Glaze Glazing Removal Removal Exam." Temp.

Thickness Glazev Thickness :Glaze (Inches) Level (Inches) Level It will be noted from a consideration of theresults of TableI, that as temperature is increased, the intensity of the glaze passes through a maximum. Ithas been observed that as the diflferential between the glaze im: pression tempertaure is reduced, longer periods of heating to remove glaze are required. Thus, whereas in Example 7, the glaze level of the spot impressed at 160 C. is only 1, nevertheless, the two minute after-treatment at the same temperature is not'of sufficient length to render the spot glaze-free.

Patented Mar. 29, 19 60- The results of a similar series of tests are shown in the graph of Figure 3. The test swatches are of the same structure as those described in the examples of Table I. Glaze is impressed at various temperatures and the fabrick thickness at the glazed spot is measured. A heat treatment period of 90 seconds at 150 C. is employed to remove glaze and the fabric thickness is again measured. Thickness in inches as ordinate is plotted against glaze impression temperature for each of the conditions as abscissa, i.e., as glazed and after heat treatment to remove glaze. Thus the lower curve indicates the thickness of the swatch after impression of the glaze. The upper curve indicates thickness of the impressed spot on the swatch after heat treatment to remove glaze as indicated. The fabric thickness prior to either glaze impression or heat treatment to remove glaze is .022 inch. Heat treatment of the original glazefree swatch increases its thickness to 0.0245 inch. It will be noted from a comparison of the two curves that as the, differential between the temperature at which the glaze is impressed and at which the fabric is treated to remove glaze decreases, the heat treatment to remove glaze has less effect upon fabric thickness. From a standpoint of glaze intensity, the shaded area indicates the region wherein heat treatment to remove glaze produces but little improvement. The conditions represented on the curves to the left of the checkered area result in essentially complete glaze removal. The conditions represented on the curves to the right of the shaded area show little or no loss of impressed glaze.

In Figure 4 the effect of repeated treatment of a fabric in accordance with the present invention is demonstrated. In this graph thickness of fabric in inches is plotted against processing cycles consisting of alternate glaze impression and heat treatment to remove glaze. At each cycle a glaze is impressed upon a swatch of the fabric as described above at 150 C. for 30 seconds under a pressure of /2 p.s.i. The swatch in a relaxed state is then heated in a circulating air oven for 90 seconds at 160 C. The lower jagged curve on the graph indicates measurement of thickness in inches of the glazed spot of the swatch after each operation over a series of cycles. The original swatch has a thickness of .0225 inch. After the first glaze impression it is reduced to .022 inch. The first post-glaze heat treatment thereafter increases the thickness to 0.0235 inch. The top curve of the graph indicates the thickness in inches of the unglazed portion of the swatch during the various cyclic operations. The ends of each of the curves indicated by a broken line illustrate the effects on fabric thickness of a series of heat treatments without intermediate glaze impressions.

The utility of a heat treatment prior to subjecting the fabric to glaze-impressing conditions to increase its resistance to glaze is demonstrated by the above example. It will be noticed that the second glaze impression fails to reduce the thickness of the swatch to less than its thickness before the first glaze-impression. This is true in later glaze impressions as well, i.e., the later glaze impressions never reduce fabric thickness as much as did the initial one. Furthermore, it has been observed that such a prior heat-treatment increases the range of temepratures at which the fabric may be pressed without glaze impression. A similar increased temperature range effect is attained by coating the fabric with a crosslinked polymethyl siloxane polymer sold under the name of DeCetex 104 by the Dow Corning Company of Midland, Michigan. The fabric is padded with a dilute aqueous suspension of the polymer after which the resin is heat cured.

In an attempt to simulate the efiect of repeated dry cleaning and heat treatment to remove glaze, thirteen fabric swatches as listed in Table II are subjected to twenty cycles of an operation involving agitation in Stoddard solvent, drying at 65 C. for to minutes,

and a glaze impression by steam hand ironing followed by a glaze removing heat treatment by heating the swatch in an oven for 2 minutes at 160 C.

TABLE II Example Fabric (As described for Examples 1-7 inclusive.)

A 6.4 ounce per square yard 2 x 2 dark brown twill woven from the yarn of Example 8.

A 6.3 ounce per square yard 2 x 2 dark brown twill woven from a mixed yarn of 20% wool and 2% inch, 3 denier per filament copolymer of 94% acrylonitrile and 6% methyl acrylate.

A 6.4 ounce per square yard 2 x 2 brown and tan twill woven from the mixed yarn of Example 10.

A 6.5 ounce per square yard 2 x 2 dark brown twill woven from a mixed yarn of 20% wool and 80% 2% inch 3 denier per filament polyacrylonitrile.

A 5.2 ounce per square yard plain navy blue tropical woven from the mixed yarn of Example 12.

A 3.1 ounce per square yard, plain red challis woven from the yarn of Example 8.

A 3.2 ounce per square yard plain navy challis woven from the yarn of Example 8.

A 5.0 ounce per square yard gold knit jersey knitted from the yarn of Example 8.

A 5.0 ounce per square yard navy knit jersey knitted from the yarn of Example 8.

A 4.5 ounce per square yard green knit jersey, knitted from a 2% inch 3 denier per filament polyacrylonitrile.

A 4.7 ounce per square yard gray heatherknit jersey,

knitted from the yarn of Example 10.

A 4.8 ounce per square yard green knit jersey, knitted from the yarn of Example 10.

Various properties of the above fabrics are observed after 5, 10 and 20 cycles of the simulated dry cleaning and glaze removal operations. The results are listed in Table III. In the table the positive numbers indicate improvements while the negative numbers indicate a deleterious change. The ratings employed are:

To restore a fabric to its glaze-free condition it is subjected to a glaze removal temperature, i.e., a temperature at least about that temperature at which the glaze is impressed. It is preferred to subject it to a temperature in excess, i.e., at least 10 to 15 C. above that temperature at which the glaze is impressed. Lower temperatures are efiiective provided the exposure period in increased. In general, a treatment of about to 180 seconds at. C. is effective in removing glaze impressed during commercial dry cleaning and pressing operations. No harmful effects have been observed upon any fabric even when much longer periods of exposure at this temperature were employed. Temperatures high enough to cause dye sublimation or scorching are to be avoided. While heating in air is usually most convenient, the fabric may be heated in a high boiling liquid which will accomplish cleaning and glaze removal in one step. Any inert gas may be employed. Heat may be supplied by infrared as demonstrated below.

A brown suit of the 2 x 2 twill of the construction outlined in Examples 1 to 7 inclusive is highly glazed by a series of commerical dry cleanings and pressings. It is then subjected to an infra-red lamp (130 C.) for 30 minutes. At the end of this period the suit is essentially glaze-free. The use of infra-red is particularly valuable in removing localized glazed spots without the necessity of a large heating cabinet.

All fabrics show some susceptibility to the impression of glaze. However in the case of fabrics produced from yarns of natural fibers, this glaze is usually relatively easily removed by steam. Such treatment temporarily swells natural fibers after which they relax into their' original glaze-free positions. On the other hand, glaze upon fabrics containing yarn produced from synthetic, thermoplastic polymers is normally not removable with steam. Flattening of the crowns of the yarn bundle in such a fabric normally places a permanent deformity in them which does not respond to simple steaming. Fabric containing yarn produced from a fiber-forming acrylonitrile polymer is particularly sensitive in this respect. The invention described herein is therefore particularly useful in the trteatment of such fabric, but is not limited thereto.

By the term a yarn produced from a fiber-forming acrylonitrile polymer is meant a filament or fiber or the like formed by extrusion of a polymer of acrylonitrile such as is illustrated in U.S. Patent No. 2,436,926 to R. A. Jacobson dated Mar. 2, 1948. The term acrylonitrile polymer is intended to include any polymer of acrylonitrile, including polyacrylonitrile (i.e., the homopolymer), wherein the acrylonitrile component constitutes about 85% or more of the polymermolecule calculated as CH =CH--CN. Among the compounds that may be copolymerized with acrylonitrile may be mentioned 2- vinyl pyridine, 4-vinyl pyridine, 5-ethyl-2-vinyl pyridine and 2- or 4-vinyl quinoline. Such'copolymeric materials are shown in U.S. Patent No. 2,491,471 to H. W. Arnold, dated December 20, 1949. The yarn may be 100% acrylonitrile polymer or it may contain a substantial proportion (i.e., up to about 60%) of another natural or synthetic fiber such as wool, cotton, flax, silk, polyester, polyamide and the like. The fabric may be woven, knitted, felted or the like from the acrylonitrile yarn or a mixture of yarns.

The following examples in Table IV demonstrate the application of the processes of the present invention to a fabric containing yarn produced from a fiber-forming polyester. In each example the test swatch is a conventional 2 x 2 brown and white twill of 5 denier per filament 2% inch staple of polyethylene terephthalate.

TABLE IV Control Ex. 22 1 Glaze impression Temp., 0.

Glaze Fabric Glaze Fabric Level Thickness Level Thickness l Post-glaze heat treatment at 160 C. to: 3 minutes.

It has been observed that plain colored fabrics will glaze considerable more than those with h'eather'ed or mottled designs. Dark shades shine more than light. Twills glaze much more than tropicals and challis. Plain circular-knit fabrics are more glaze-sensitive than twills. Fabric produced from yarn spun from fibers of low denier per filament (i.e., 1.5) glaze more readily than those where the denier per filament is relatively high (i.e., 6 to 10).

Relaxed conditions for tailored fabrics can be conveniently attained by hanging them in a heat cabinet or oven. It is preferable that permanent creases, such as in a pleated skirt, hang vertically. An overfed pin tenter is recommended for the treatment of larger pieces of fabric. I

Many modifications of the above disclosed invention will be apparent to those skilled in the art from a reading of the above description without a departure from the inventive concept.

What is claimed is: p a

1. A process for the removal of a heat and pressure impressed glaze. the said glaze having been impressed at a 9 temperature below about 150 C. from a fabric containing a yarn produced from a fiber-forming polymer of acrylonitrile which comprises subjecting the glazed fabric, in a relaxed condition to a temperature at least about the temperature of glaze impression and below the temperature at which fusion occurs for a period of from about to about 180 seconds.

2. A process for the removal of a heat and pressure impressed glaze from a fabric containing a yarn produced from a fiber-forming acrylonitrile polymer wherein the said glaze is impressed at a temperature no higher than about C., which comprises subjecting the glazed fabric, in a relaxed condition, to a temperature of at leastabout C. for from about 120 to about seconds.

References Cited in the file of this patent UNITED STATES PATENTS 7 OTHER REFERENCES Americas Fabrics, by Zelma Bendure and Gladys Pfeiffer, pages 540, 541, The Macmillan Co., New York, 1947.

Textile World, November 1949, pages 140-141.

Why Decating Improves the Finish of Fabrics, by Van Vlaanderen Machine Co., Paterson, N.J., page 3, received in Div. 21, May 9, 1950.

UNITED STATES PATENT OFFICE CERTIFICATE OF CRRECTION Patent No. 2330 099 March 29 '1960 Lewis Delmar Swan It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column l line 51, after "Figure" insert l column 2, line 314, after "A" insert pressure line 41 for "over" read oven line 61, for "tempertaure" read temperature column 3, lines, 4 and 5 for "'fabrick" read fabric line 63, for "temepratures" read temperatures column 4, line 64, for "in'f first occurrence, read is column 5, line 24, for tr'teatme'nt" read treatment line 34, for

*"polymermolecule" read polymer molecule column 6; line 2 for "considerable" read'-=- considerably 5 line 48 list of References Cited,- under FOREIGN PATENT-S for "466 648" read 466,684 v I Signed and sealed this 20th day of September 1960.,

(SEAL) Attest:

KARL H. AXLINE Y ROBERT C WATSON Attesting Officer Commissioner of Patents 

1. A PROCESS FOR THE REMOVAL OF A HEAT AND PRESSURE TEMPERATURE BELOW ABOUT 150* FROM A FABRIC CONTAINING A YARN PRODUCED FROM A FIBRE-FORMING POLYMER OF ACRYLONITRILE WHICH COMPRISES SUBJECTING THE GLAZED FABRIC, IN A RELAXED CONDITION TO A TEMPERATURE AT LEAST ABOUT THE TEMPERATURE OF GLAZE IMPRESSION AND BELOW THE TEMPERATURE AT WHICH FUSION OCCURS FOR A PERIOD OF FROM ABOUT 120 TO ABOUT 180 SECONDS. 